Transketolase contains Mg++ and a tightly bound thiamin pyrophosphate and transfers a glycoaldehyde group from D-xylulose 5-phosphate to D-ribose 5-phosphate to form the seven-carbon sugar phosphate D-sedoheptulose 7-phosphate and D-glyceraldehyde 3-phosphate, which is an intermediate of glycolysis. See Lehninger, BIOCHEMISTRY, 2d ed., at pages 468-49 (1975). Genes which code for transketolase have been isolated and described from Mus musculus (Schimmer et al., J. Biol. Chem. 271, 4993-98, 1996), from Saccharomyces cerevisiae (Flechter et al., Biochemistry 31, 1892-96, 1993; Sundstrom et al., J. Biol. Chem. 268, 24346-52, 1993; Schaff-Gerstenschlager et al., Eur. J. Biochem. 217, 487-92, 1993), from Hansenula polymorpha (Janowicz et al., Nucl. Acids Res. 13, 3043-62, 1985), from human erythrocytes (Abedinia et al., Biochem. Biophys. Res. Commun. 183, 1159-66, 1992; McCool et al., J. Biol. Chem. 268, 1397-404, 1993), from Rhodobacter sphaeroides (Chen et al., J. Biol. Chem. 266, 20447-52, 1992) and from Escherichia coli (Sprenger, Biochem. Biophys. Acta 1216, 307-10, 1992; Tida et al., J. Bacteriol. 175, 5375-83, 1993). Two transketolase isoforms have been described in plant tissues (Murphy and Walker, Planta 155, 316-20, 1982). Because of the importance of this enzyme in a variety of metabolic pathways, there is a need in the art to identify additional human transketolase-like enzymes which can be regulated to provide therapeutic effects.